1. Field of the Invention
The present invention relates to a heating time control apparatus and a method thereof for a microwave oven, and particularly to an improved heating time control apparatus and method thereof for a microwave oven capable of advantageously computing an optimum cooking time without controlling food amount to be cooked or a predetermined initial cooking time by detecting varying rate of smell of the food thereby computing a cooking time in accordance with the detected varying rate of smell.
2. Description of the Conventional Art
Conventionally, in heating food using a microwave oven, an optimum heating time of food is determined by various factors such as an initial temperature and amount of food to be cooked, desired heating temperature and power of a microwave oven. One such method of determining an optimum heating time is disclosed in U.S. Pat. No. Re. 31,094, which detects an optimum food state using rapidly varying levels of moisture from food being cooked and a second heating time in accordance with the detected food state using a predetermined algorithm. However, in cases where moisture sharply increases as when cooking frozen food or where the moisture varying rate is low due to a food's particular characteristic during heating, there may be a big difference between a computed heating time and an actual heating time. In addition, in the case of warming food, the time during which the moisture amount increases sharply exceeds the time at which the level reaches 100.degree. C. which is larger than the warming temperature of 60.degree.-85.degree.. Therefore, there is a big difference in heating time because the entire heating time is computed based upon a time when rapid changes of moisture occurs.
Accordingly, in an attempt to resolve such problems, U.S. Pat. No. 4,336,433 discloses a method, which is directed to differing a predetermined constant K of determining a food heating time in accordance with the kind and amount of food to be cooked in determining a second heating time. However, even though the constant K is computed in accordance with the kind and amount of food, since the initial state of food is not considered, there are still discrepancies between the computed heating time and the actually required heating time when frozen food is cooked and a food warming function is used. In addition, in determining the constant K, it takes much time because it comes from an experimental basis.
Furthermore, in an attempt to solve the above problems, U.S. Pat. No. 4,335,293 discloses an approach intended to set a time of increasing a predetermined time at a minimum of moisture variance as a first heating time and to set a second time in accordance with the set first heating time. However, the above retention has largely retained the same problems as in the prior art.